Preheat the oven to 180C/350F/Gas 4. Grease and line a 450g/1lb loaf tin.
In a large bowl beat together the yoghurt, vegetable oil, lemon and orange zest and eggs until light and fluffy. Sift in all the dry ingredients and mix until just combined.
Spoon the mixture into the loaf tin and bake for about 45 minutes. (Test the cake by inserting a skewer into the centre. If the skewer comes out clean, the cake is done.)
Remove from the oven and leave to cool a little in the tin.
Meanwhile for the glaze, warm the marmalade and orange juice until the marmalade melts. Pour the glaze over the cake and set aside to cool completely.
Remove the cake from the tin and serve with lashings of Greek-style yoghurt.